Put a tailgate spoiler from a 1500 on your truck. They are on the ½ tons for a reason. It also makes a nice handle for lifting/lowering the tailgate.

Buy a Smarty Jr and run it on the econ mode (level 1).

 

I am getting the best mileage running larger tires (H-2s, 315s) on my 2wd, 6 speed. It was good before, but I'm real happy with it now!

 

I have been running Air Tabs on my trucks and motorhome. They are vortex generators (like what you see on airplanes) and I calulate about a 5% increase in fuel milage as they reduce considerably the negative pressure or air turbulance in the bed.

 

Where do you mount the Air Tabs on a pickup truck?

 

The point they made in the end as well as some other independent tests is that tailgate up/down, toneau, cap, or nothing will vary from vehicle to vehicle, so you can't make sweaping generalizations and you won't know the effects until you try it at the speeds you intend to drive and with your driving style..

 

For most trucks a larger tire diameter won't make much mpg difference because the OEM ratios already have you in the flat part of the mileage vs rpm curve for the motor (about 2000rpm). If you have 410s, or an early (05 or 06) G56, however, the corresponding mileage sweet spot is like 50 mph (although they can pull a good size house off its foundation). And 65 mph is on the steep part of the mileage drop off curve. I gained 10% in mpg, with all the corrections factored in, by simply going to 315s and the driving the same 65 mph.

Here are three free tips that will probably improve your milkeage more than mods. I don’t know of any mods that has a decent payback except for the specific models mentioned above. There are certainly costly mods that will improve economy.

First, plan your driving ahead so you don't need to use the brakes. Using brakes uses up energy you just paid dearly for.

Second, get up to your desired road speed promptly, not full throttle but prompt. Someone that did the math calculated that using a bit more fuel to get up to your desired road speed but for a shorter period of time gives you better mileage than using less fuel over a longer time.

Third, keep your rpms in the optimum range for mileage, which is typically your peak torque (not horsepower) rpms. For the Cummins, someone did a test, and I don't remember which truck year or model, that 1750 rpm is optimum for mileage. The curve is pretty flat until 2100 rpm or so, I think, where it drops off steeply. So keep the rpms below 2100.

Other misc thinks like keeping your weight down, pump up the tire pressure, and don't add air resistance will help some.

By the way, its this steep curve that more than makes up for the additional rolling resistance of larger tires in 410 or early G56 equipped trucks.

If you already are doing these things, then nevermind. You are about as good as your going to get without spending a fortune.

 

hey Capt Ron,
the myth that was busted was slight increase to no fuel mileage change with the tail gate up. you accually will decrease you mileage with it down. has some thing to do with the aerodinamic of the air coming over the top of the truck and down on the tailgat with it down. air acually slams down on the tailgate like a hammer. did not believe it until i say it in the wind tunnel. i drove with mine down for years until i say that. it was pretty interesting.

 

I have an early 05' with the G56.I am in need of some new tires and getting ready to buy them. Are you saying I can improve my mileage by going to 315's?

Maybe this will make up for my lost mileage from my AFE stage I filter......

 

On the point of myth Busters yah I didnt agree with there tests. You can't do a test like that with 2 trucks, something as simple as different tread depths will change the fuel milage. What is one wheel bearing is a little tighter then another, so many factors that could change 30-50 miles on a tank. I keep my tailgate up cause there is always crap in the back of my truck lol. I have several hitches alone I keep back there, dont want one in someones wind sheild.


I did a neat test when I spent a week in Pa, was in the mountains pretty good most the speed limits where 40-45 area. If I did 45-50 with od on and tc locked (via button) I would only get around 13-14 mpg, with od off so I am in 3rd gear and tc locked doing 35-40 mph it went to 18-19 mpg. There where some pretty steep grades to get to where we stayed, I ran about half a tank each way. The differance was running at around 1200-1300 rpm and 1600-1800 rpm and the higher rpm was better econemy.

I am a beliver that running under 1500 is bad for fuel economey unless 1. You are in FL or somewhere where the roads are very flat. 2. there is no head wind or stop and go traffic. When ever I am on 35-40 mph roads here in KY I use 3rd with the tc locked up, helps alot.

I now have the Goerend tc, should have got it a little tighter but its amazing. Without useing the lock up button and driveing the same I used to I have picked up 2.5 mpg in the city. Reason is now I can use a light pettal and get light rpms, before the engine would rev to 2k just going up a 1 or 2% grade road, now its only 100-200 rom higher then when I hit the lock up button.

Engines are most efficent useually at peak torque area, so you figure around 1800 plus or minus a few hundred rpm. If you mod the truck so its peak torque is higher like race motors then the efficentcy moves with it. Also you have look at where aerodynamis begin to increase at a non liner rate with speed. These are made up numbers just to get a idea. Say at 50 it takes 80 hp to maintain speed on a flat road and 55 takes 95 and 60 takes 110 and 65 takes 140 then you want to drive at 60 mph and maintain around 1800 rpm for peak efficency.

IF you drive on flat roads then you can lower the rpm, I think to many ppl in the hills try to lower there rpm, that dont work well. I can get 21-22 mpg at 70mph gps speed in my truck with my mods. If I go to 60 mph I can get 23-24 but my rpm drops alot and my egt's climb on every hill. Stock tires would prob let me get 25mpg at 60 np cause the higher rpms would keep the egts more stable.

 

Simply what works for me is driving to the sound of the turbo
whistle. I try to minimize the whistle during during all conditions,
while maintaining RPMs @ 1600 to 1800. I have a 04.5, 2wd
6 spd.

 

I know that this is geared toward semi's but there is a lot of usefull info in here





http://www.everytime.cummins.com/eve...Whitepaper.pdf

 

Mythbusters also didn't go over 55mph.... Above 55 it makes a noticeable difference with no tailgate or tailgate down..(dont prefer the latter) If your not hauling anything in the bed or just pulling a trailer try it....you will notice a .5-1.5 better mileage at least I did on both long beds. Just my .02. I tried it works for me and is best of all FREE!!!

 

What is a "tag" anyone?

 

From the articles I have read useless....

It goes in the downtube between airbox and turbo to straighten the air.

 

Forgot to mention this earlier in the thread.

If you drop your tailgate for increased mileage, you may or may not get better MPG, but you will definitely get more PCPM.

That would be Paint Chips Per Mile. I used to work with a guy that always drove his PU around with the tailgate down. He was a charter member of the tailgate-down-gets-better-mileage club. After a couple of years of doing that, his tailgate had serious chip damage, which he ate at trade in time.

Food for thought.